1. Field of the Invention
The present invention relates to a chip coated Light Emitting Diode (LED) package and a manufacturing method thereof and, more particularly, to a chip coated LED package which increases light extraction efficiency, accommodates miniaturization of a product and reduces manufacturing costs, and to a manufacturing method thereof.
2. Description of the Related Art
In general, a Light Emitting Diode (hereinafter referred to as ‘LED’) is an electric component which converts electric energy to light energy from recombination of minority carriers (electrons and holes) injected through a p-n junction structure of semiconductor and thereby emits the light. That is, when a forward voltage is applied to a semiconductor of a particular element, electrons and holes migrate through the junction of an anode and a cathode and recombine with each other. The recombined state has a smaller energy than when the electrons and the holes are separated from each other. Using this difference in energy, the LED emits light.
The range of light generated from the LED is from a red region (630 nm to 780 nm) to a blue-Ultraviolet region (350 nm) including blue, green and white. As the LEDs have advantages such as low power consumption, high efficiency, prolonged operation and lifetime, the demand therefore has been increasing.
In addition, the range of application of the LEDs has been expanded from small-sized illumination of mobile terminals to indoor/outdoor illumination, automobile illumination and backlights for large-sized Liquid Crystal Displays (LCDs).
FIG. 1 is a longitudinal sectional view illustrating a conventional LED package. As shown, the conventional LED package 10 includes a package body 11 having an upwardly-open cavity formed therein, a lead frame 12 provided integrally to the package body 11, a light emitting chip 14, which is a light emission source for generating light when power is applied, wired bonded by a plurality of metal wires 15 so as to be electrically connected to the lead frame 12 and a transparent resin encapsulant 17 filled in the cavity to protect the light emitting chip and the metal wires from the outside environment.
The transparent resin encapsulant 17 is made of a transparent resin such as epoxy to pass the generated light to the outside.
In the meantime, in a case where the light emitting chip 14 is provided as a blue light emitting device, a fluorescent material is included in the transparent resin encapsulant 17 to obtain desired white light.
Such a fluorescent material is a wavelength-converting means that converts a first wavelength of blue light emitted from the light emitting chip 14 to a second wavelength of white light. The fluorescent material is made of Yitrium Aluminum Garnett (YAG)-based, Terbium Aluminum Garnett (TAG)-based, or silicate-based powder, and is mixed in the transparent resin, the main substance of the transparent resin part 17.
However, in the process of irradiating the blue light generated from the light emitting chip 14 to the outside, beams of the blue light propagate for different lengths before being converted into white light due to the structure of the transparent resin encapsulant 17 containing the fluorescent material. This adversely causes non-uniform color temperature according to the irradiation angles of white light.
Moreover, in this structure, the light emitting chip 14 and the metal wires 15 come in contact with the YAG-based, TAG-based and Silicate-based fluorescent material contained in the transparent resin encapsulant 17. Thus, made of heavy metal-based powder having electric conductivity, the YAG-based, TAG-based and Silicate-based fluorescent material may cause leakage current degrading the light efficiency of the light emitting chip 14 during light emission, ultimately undermining the reliability of the package.
Therefore, as an approach to prevent leakage current due to the contact between the fluorescent material contained in the transparent resin encapsulant and the metal wires 15, the light emitting chip 14 is flip-chip bonded on a submount (not shown) via a plurality of bump balls, the submount is mounted on the lead frame 12 of the package body 11, and the submount and the lead frame 12 are wire bonded by the metal wires so as to be electrically connected to each other.
Then, the transparent resin containing the fluorescent material is filled in the cavity of the package body 11 or is applied to cover only the light emitting chip 14 flip chip bonded on the submount, thereby forming the transparent resin encapsulant 17.
However, in this structure of wire bonding the submount having the light emitting chip 14 mounted thereon with the lead frame 12, it is necessary to ensure a sufficient size of the submount to which the ends of the metal wires are bonded. This limits miniaturization of the package, complicates the manufacturing process and increases the manufacturing costs.